Mahathir Mohamad is on course to become the world's oldest elected leader at 92, after a shock victory in Malaysia's bitterly fought election.

The former PM came out of retirement and defected to the opposition to take on his one-time protégé Najib Razak, beset by corruption allegations.

His historic win has ousted the Barisan Nasional (BN) coalition, which has been in power since independence in 1957.

Jubilant Mahathir supporters filled the streets as the victory became clear.

Mr Najib has said he will "accept the verdict of the people", but correspondents say a smooth transition to power is not a given after such a major political upheaval.

No single party within the coalition won a majority, so technically it now rests with Malaysia's king to decide who forms a government.

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How have people reacted?

"Yes, yes, I am still alive," Mr Mahathir told a news conference in the early hours of Thursday. He said his coalition would not seek revenge but would "restore the rule of law".